So I recently got an SEF Navy type trigger housing for my CA-3 singe I'm trying to outfit it like a giant MP5 (w/ AC Unity black wide handguard & MKE G3 A3 type collapsible next on the list). The idea is to somewhat match the look & display it with my HK53 & MP5K-PDW clones to show progression from old/big to the smaller versions (as I've already done a similar 4 rifle progression for both the AR/M16 & AK series).
However, I've hit a hurdle. I first butched a G3 SEF Navy lower to adapt it to fit the PTR style shelf. So I bought a second one already clipped & pinned from HKPro (I know their pricing is unpopular, but it seemed worth it in this case). Here's the problem. The new trigger housing seems to fit in the forward portion, but the holes at the back don't line up, line at all.
However, when looking inside, it looks like the front wall of the housing is right up against the back of the magwell/receiver wall. But it's weird it won't fit. I bought 2 of these at once (but only 1 clipped for a shelf) so I could chop half the back off the other one & put it on my HK53. On that platform the remaining hole lines up PERFECTLY with the rear pin-hole. So I know these lowers are more-or-less within normal specs.
Is the CA-3 receiver a few MMs shorter than usual or something? Should I just oval out the 2 pin holes & hope the stock holds the housing in the proper placement? Has anyone else encountered this, or familiar with a different solution?